Ceratopteris
Encyclopedia
Ceratopteris is the only genus
among homosporous ferns that is exclusively aquatic. It is pan-tropical.
Ceratopteris is also important in the study of pteridophytes because it is a commonly used model organism
for use in genomic
studies, due to the ease and rapidity with which it can be grown in laboratories
. Patented strains of this plant have been developed.
Plants of this genus have also been used for food, as a green, with the common name "water lettuce." However, it is now known that these ferns are also carcinogenic if ingested.
, within the Pteridaceae
.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
among homosporous ferns that is exclusively aquatic. It is pan-tropical.
Description
Erect aquatic or subaquatic ferns of moderate size. Rhizome short, fleshy, horizontal and ascending to erect, loosely rooted in the mud or +/- floating, radial, dictyostelic with numerous meristeles and medullary strands, young parts bearing thin, ovate, +/- cordate, clathrate scales. Fronds stipitate, the stipes fleshy, with numerous longitudinal air canals, abaxially rounded and ribbed, adaxially flattened, vascular bundles in a peripheral ring, one with each rib and several to the adaxial side, and several smaller medullary strands; lamina dimorphic, sterile fronds +/- spreading, 2 - 3-pinnatifid with broad membranous lobes, venation reticulate without included free veinlets, often with proliferous buds in the axils; fertile fronds erect, longer, narrower and more divided than the sterile, the lobes strongly recurved to completely cover the adiaxial surface, venation longitudinal, branching at the bases of the lobes. Sporangia solititary, scattered along the veins, exindusiate but protected by the continuous reflexed margin of the lamina, large, short-stalked, annulus broad, irregular, of 30 - 70 thickened cells, or lacking, containing 16 to 32 spores. Spores large, trilete, ribbed with irregular long meshes.Distribution
A widespread genus of four to six species in the humid tropics.Ceratopteris is also important in the study of pteridophytes because it is a commonly used model organism
Model organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. Model organisms are in vivo models and are widely used to...
for use in genomic
Genomics
Genomics is a discipline in genetics concerning the study of the genomes of organisms. The field includes intensive efforts to determine the entire DNA sequence of organisms and fine-scale genetic mapping efforts. The field also includes studies of intragenomic phenomena such as heterosis,...
studies, due to the ease and rapidity with which it can be grown in laboratories
Laboratory
A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...
. Patented strains of this plant have been developed.
Economic Use
Ceratopteris is a fairly popular aquarium plant, often sold under the name "water sprite." It may be grown as an emersed but natant (floating) plant, or as an immersed plant rooted in the substrate. The most common species in use in aquaria are C. thalictroides and C. pteridoides.Plants of this genus have also been used for food, as a green, with the common name "water lettuce." However, it is now known that these ferns are also carcinogenic if ingested.
Higher Classification
Ceratopteris was long placed in the monogeneric family Parkeriaceae, thought to be unique because of its aquatic adaptations. However, recent genetic analysis has shown it to be clearly allied with AcrostichumAcrostichum
Acrostichum was one of the original pteridophyte genera delineated by Linnaeus. It was originally drawn very broadly, including all ferns that had sori apparently "acrostichoid", or distributed in a solid mass across the back of the frond, rather than organized in discrete sori...
, within the Pteridaceae
Pteridaceae
Pteridaceae is a large family of ferns in the order Pteridales. Members of the family have creeping or erect rhizomes and are mostly terrestrial or epipetric...
.
Species
(some authorities recognise only four species)- Ceratopteris cornuta (P. Beauv.) Le Prieur; Ann. Sci. Nat. 19: 103. t. 4A (1830)
- Ceratopteris gaudichaudii Brongn.; Bull. Soc. Philom. 187 (1821)
- Ceratopteris pteridoides (Hook.) Hieron.; Bot. Jahrb. Syst. 34: 561 (1905)
- Ceratopteris richardiiCeratopteris richardiiCeratopteris richardii is a fern species belonging to the genus Ceratopteris, one of only two genera of the Ceratopteridaceae family. It is one of several genera of ferns adapted to an aquatic existence. C. richardii was previously regarded as being part of the species Ceratopteris thalictroides...
Brongn.; Dict. Class. Hist. Nat. 3: 351 (1823) - "C-fern" - Ceratopteris thalictroidesCeratopteris thalictroidesThe species Ceratopteris thalictroides is a fern species belonging to the genus Ceratopteris, one of only two genera of the Ceratopteridaceae family. The species represents a special living form of ferns, and is thus of great botanical interest...
(L.) Brongn.; Bull. Sci. Soc. Philom. Paris, sér. 3, 8: 186 (1821)